Prostate cancer is the second leading cause of death from cancer in men in the U.S. and mortality from prostate cancer is invariably due to tumor metastasis. Our overall goals for this second competitive renewal application therefore continue to be to understand prostate cancer invasion and metastasis with a focus, in this application, on lymphatic metastasis and malignant ascites. During the previous funding period we have obtained novel insights into metastasis-permissive environments and the role of hypoxia in this process. Based on these insights, and as a logical progression of understanding the metastatic phenotype in prostate cancer, in Aims 1 and 2 we have focused on understanding the role of hypoxia in allowing lymphatic and ascites metastatic dissemination from metastasis-permissive environments, and on characterizing the role of extracellular matrix in this process, using noninvasive optical and MR imaging. In Aim 3 we intend to investigate the role of cancer cell- lymphatic endothelial cell interactions in cancer cell invasion under hypoxic conditions, using our MR compatible cell perfusion system. The studies proposed here will characterize extracellular matrix integrity and structure and the role of lymphatic endothelial cells in microenvironments that permit metastasis, and the role of hypoxia in facilitating metastasis from these environments. These studies will also provide insight into the dynamics governing interstitial transport and the mechanisms of clearance of macromolecular fluid in tumors in hypoxic and normoxic tumor regions. The proposed studies will continue to identify vascular, physiological and metabolic characteristics which promote invasion and metastasis. This information is critical for developing strategies to prevent metastasis from prostate cancer. PUBLIC HEALTH RELEVANCE: Lymphatic metastasis and malignant ascites are major causes of poor prognosis and quality of life in prostate cancer patients. Hypoxic environments frequently exist in solid tumors and result resistance to therapy. Here we intend to use noninvasive MRI methods as well as optical microscopy and immunohistochemistry to understand the role of metastasis-permissive environments and hypoxia in altering interstitial fluid transport and the extracellular matrix, and in lymphatic metastasis and malignant ascites in preclinical studies of prostate cancer.